FIG. 8 is a flowchart which shows a flow of an image forming system which includes an inkjet printer and a pre-applying liquid applying apparatus.
As shown, a recording medium W which includes an elongated continuous paper sheet, for example, which is sent out from a roll 31 is initially sent into a pre-applying liquid applying apparatus 32, and pre-processing is performed with a pre-applying liquid such as the above-described suppressing agent being applied onto the recording medium W. The system is arranged such that, next, the processed recording medium W is sent into an inkjet printer 33, onto which recording medium W ink droplets are ejected, so that a desired image is formed, and then it is sent to a post-processing apparatus (not shown), so that predetermined post-processing is performed.
FIG. 9 is an overview configuration diagram of a related-art pre-applying liquid applying apparatus for an inkjet printer.
As shown, a transfer roller 1, a peripheral face of which is covered with an elastic body such as rubber, is rotatably supported via a bearing at one end of an oscillatable TR arm 2, a TR spring 3 is connected to the other end of the TR arm 2, and a base end of the TR spring 3 is fixed to a frame. A tensile force of this TR spring 3 acts in such a direction as to oscillate the TR arm 2 to push the transfer roller 1 to the applying roller 5 side.
A TR cam 4 is in contact with the TR arm 2 and has attached a motor (not shown) which rotates the TR cam 4 and an angular sensor (not shown) which detects a rotational position of the TR cam 4. Such a rotation of the TR cam 4 makes it possible to oscillate the TR arm 2 against the tensile force of the TR spring 3 as described above, and move the transfer roller 1 in a direction away from the applying roller 5.
A peripheral face of this applying roller 5 is covered with an elastic body such as rubber, and the applying roller 5 is rotationally driven in an arrow direction by a motor 6. A squeeze roller 7, which abuts against the applying roller 5, is arranged such that it rotates with the applying roller 5.
This squeeze roller 7 is rotatably supported via a bearing at one end of a SQZ arm 8 which is oscillatable; a SQZ spring 9 is connected to the other end of the SQZ arm 8; and a base end of the SQZ spring 9 is fixed to a frame. A tensile force of the SQZ spring 9 acts in such a direction as to oscillate the SQZ arm 8 to push the squeeze roller 7 to the applying roller side 5.
A SQZ cam (OC) 10 is in contact with the SQR arm 8 and has attached a motor (not shown) which rotates the SQZ cam (OC) 10 and an angular sensor (not shown) which detects a rotational position of the SQZ cam (OC) 10. Such a rotation of the SQZ cam (OC) 10 may oscillate the SQZ arm 8 against the tensile force of the SQZ spring 9 as described above, and move the squeeze roller 7 in a direction away from the applying roller 5.
Pre-applying liquid 12 is contained inside a case 11 which tucks in the applying roller 5 and the squeeze roller 7. The case 11 is arranged as a container which is made airtight such that the pre-applying liquid 12 does not leak out of the case, and a water level of the pre-applying liquid 12 is maintained constant.
At a portion which opposes the transfer roller 1 of the case 11 is provided an opening portion, at which opening portion a shutter 13 for suppressing evaporation of moisture of the pre-applying liquid 12 is provided such that it can open and close. The shutter 13 is arranged to open when the transfer roller 1 contacts the applying roller 5.
The water level of the above-described pre-applying liquid 12 is monitored with a water-level sensor 14, so that when the water level becomes low, a supply valve 15 is opened and a supply pump 16 is driven to send the pre-applying liquid 12 within a pre-applying liquid tank 17 into the case 11. The supply valve 15 is closed when a desired water level is reached to stop the supply pump 16, thereby maintaining the water level of the pre-applying liquid 12 within the case 11 constant.
The squeeze roller 7 is positioned such that it soaks in the pre-applying liquid 12; the squeeze roller 7 is arranged such that the applying roller 5 is rotated by the motor 6, so that the applying roller 5 rotates with the squeeze roller 7, making it possible to supply the pre-applying liquid 12 to a nip position of the squeeze roller 7 and the applying roller 5 due to viscosity of the pre-applying liquid 12.
The pre-applying liquid 12 passes through a nip portion of the above-described applying roller 5 and the squeeze roller 7, and forms a layer of the pre-applying liquid 12 in a uniform minute amount on a surface of the applying roller 5. The recording medium W such as a sheet of paper is pushed against the applying roller 5 by the transfer roller 1, so that the pre-applying liquid 12 in the uniform minute amount is transferred onto the recording medium W for applying. The present apparatus configuration makes it possible to achieve uniform minute amount applying of the pre-applying liquid 12 onto the recording medium W.
Moreover, taking into account characteristic degradation due to thickening of the pre-applying liquid 12, a liquid-discharge valve 18, a liquid-discharge pump 19, and a liquid-discharge tank 20 are provided in order to discharge the pre-applying liquid 12. The liquid-discharge valve 18 is opened and the liquid-discharge pump 19 is driven, so that the pre-applying liquid 12 within the case 11 that is degraded is discharged to the liquid-discharge tank 20.
A related-art pre-applying liquid applying apparatus for the inkjet printer is disclosed in Patent document 1,for example.